Power generation has conventionally been performed by recovering waste heat energy released at plants, incineration facilities and the like, with energy savings being achieved by the electrical energy that is obtained by this power generation being reused. In recent years, measures have been taken to realize further energy savings by performing power generation by also recovering the waste heat energy of low-temperature waste heat that has hardly been recovered conventionally. In order to recover electrical energy from this kind of low-temperature waste heat, a Rankine cycle waste heat power generation device that uses a low-boiling-point working medium has been proposed (for example, Patent Document 1).
Patent Document 1 discloses an exhaust heat power generation device that is provided with a steam generator, introduces an exhaust heat medium from an exhaust heat source to the steam generator, guides the generated working medium steam to an expansion machine, generates electricity by driving a generator with this expansion machine, leads discharged working medium steam to a condenser, cools/condenses the working medium steam by a low-heat medium from a low-heat source, and supplies this condensed working medium liquid to the steam generator. In this exhaust heat power generation device, a working medium steam superheat degree control member is provided that controls to a predetermined target value the superheat degree of the working medium steam at the steam discharge port or corresponding portion of this steam generator by varying the flow rate of the working medium liquid supplied to the steam generator.